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From a Room in Jerusalem to the Empire

How the Movement Grew

In 30 AD, there were perhaps a few hundred Christians, all in Jerusalem. By 300 AD, there were millions, spread across the Roman Empire.

The numbers, the patterns, and what they mean

In 30 AD, there were perhaps a few hundred Christians, all in Jerusalem. By 300 AD, there were millions, spread across the Roman Empire. How did a small, persecuted, predominantly lower-class movement grow into the dominant religion of the empire? This page examines the evidence and the sociological models that have been proposed to explain it.

The Numbers

The most influential modern study is Rodney Stark’s The Rise of Christianity (1996). Stark, a sociologist of religion, estimated that the Christian movement grew at roughly 40 percent per decade, from about 1,000 members in 40 AD to somewhere between 6 and 7 million by 300 AD — roughly 10 percent of the empire.

Keith Hopkins, a British ancient historian, argued for a lower estimate: perhaps 3.4 million by 300 AD, or about 5 percent of the empire. His model assumes growth of about 30 percent per decade. His estimate is more conservative, but the direction is the same.

The Estimates

Rodney Stark40% per decade. About 6–7 million Christians by 300 AD.
Keith Hopkins30% per decade. About 3.4 million by 300 AD.
CaveatBoth estimates are inferences from fragmentary evidence. The actual numbers are unknown. What is clear is that the movement grew steadily and substantially.

What the Evidence Shows

We have three kinds of evidence for the growth of the early Christian movement.

The Evidence

LiteraryThe New Testament, the apostolic fathers, and the second-century apologists. Pliny the Younger’s letter to Trajan (c. 112 AD) is especially important: he reports that Christianity had spread not only in the cities but in the countryside, and to all classes.
ArchaeologicalChristian catacombs in Rome (from the 2nd century), Christian house churches (Dura-Europos, c. 240), and inscriptions. Christian symbols and names appear with increasing frequency over time.
StatisticalThe growth of the episcopate (bishops in major cities), the size of church buildings, and the number of Christian writers all increase substantially across the second and third centuries.

The Patterns of Growth

The movement did not grow through mass revivals. It grew through households, networks, and personal relationships. The evidence suggests several patterns.

How the Movement Grew

Household conversionWhen a household head converted, the entire household typically followed. Lydia, Phoebe, Chloe, and Nympha all hosted churches in their homes.
Urban centersThe movement spread through cities, along trade routes and Roman roads. Paul began in each new city by going to the synagogue, then to the marketplace, then to private homes.
Care for the sickChristians cared for the sick during epidemics when pagans often fled. This produced disproportionate survival rates and a reputation for compassion.
Care for widows and orphansThe church supported widows and orphans on a scale that no pagan institution matched. This was not charity as an abstraction; it was a practical survival network.
Welcoming of women and slavesWomen and slaves found in the church a status and dignity that the surrounding culture did not offer. This produced disproportionate conversion among these groups.
Higher fertilityChristians forbade abortion and infanticide and discouraged remarriage after the death of a spouse. The resulting birth rate was higher than the pagan average.

Why Sociologists Find This Interesting

Sociologists of religion have noted that the early Christian movement displays several features that social science predicts will produce rapid, sustained growth.

The movement was a social network, not a mass movement. It spread from person to person through existing relationships. Converts typically joined because someone they trusted was already part of the community.

It offered clear boundaries. Christians were visibly different from their pagan neighbors in their sexual ethics, their treatment of the poor, and their refusal to participate in Roman religious life. This produced a distinct identity.

It offered real benefits to people who joined. Sick Christians were cared for. Widows were supported. Slaves were treated as brothers. The practical benefits of membership were substantial in a world without a social safety net.

It made a claim about history. Unlike the mystery religions, which offered spiritual experience without historical grounding, Christianity claimed that God had entered history at a specific time and place. This claim could be investigated, argued about, and defended.

What the Growth Does and Does Not Show

The growth of the early Christian movement does not, by itself, prove that its claims were true. Many movements grow rapidly and are false. But it does establish that the movement was historically significant and that its growth cannot be explained solely by imperial favor or social coercion. In the first three centuries, Christianity had no imperial support and considerable imperial opposition. It grew despite persecution, not because of patronage.

The growth is one part of the historical case. The claim that the movement was founded on a hoax must explain how a hoax produced this kind of sustained, cross-class, cross-cultural growth over two centuries. That is not impossible, but it is harder than the alternative.

Sources & Reports

Every factual claim on this page is traced to a source below.

  1. Rodney Stark, The Rise of Christianity: A Sociologist Reconsiders History (Princeton, 1996).
  2. Keith Hopkins, “Christian Number and Its Implications,” Journal of Early Christian Studies 6 (1998): 185–226.
  3. Pliny the Younger, Letters 10.96–97, on the spread of Christianity in Bithynia-Pontus.
  4. On the catacombs, see the standard archaeological reports; on Dura-Europos, see Carl H. Kraeling, The Christian Building (Yale, 1967).